The present invention relates generally to semiconductor manufacturing technology and more specifically to electroplating systems using consumable anodes.
In the past in the manufacture of semiconductors, there have been numerous processes which required plating at various stages to deposit various materials on semiconductor wafers. All of these systems generally required human operator monitoring or the addition of plating materials at timed intervals. Since the addition of plating material was deemed to be one which required a certain degree of expertise and experience, it was not thought to be possible to automate this type of operation without complex, and expensive, computer equipment.
As the industry has sought to make smaller and smaller semiconductor devices with finer and finer device connections, it has been found that conventional metallization techniques for making the device connections is are inadequate for future generations of products. This has resulted in the shift from materials such as aluminum (Al) to copper (Cu).
Copper is not suited for deposition using the metallization techniques used for aluminum and is better adapted for deposition by electro- or electro-less plating processes out of a solution. With the adoption of the copper interconnect, the device connection technology, there has been a great deal of effort placed into automating copper plating technology for semiconductors. This has meant the introduction of expensive equipment. This in turn has meant that much effort has been expended in trying to reduce costs.
One of the processes for depositing copper uses a consumable primary anode in the plating chamber. As the consumable primary anode is consumed, it changes the geometry and the electromotive force in the plating chamber leading to non-uniform deposition of the copper. Non-uniform deposition of the copper leads to difficulties in following planarization steps and in defective integrated circuits around the perimeter of the semiconductor wafer.
A solution for solving this problem simply and inexpensively has been long sought by and eluded those skilled in the art.
The present invention provides an electroplating system for semiconductor wafers including a plating chamber having a consumable remote secondary anode connected by a circulating system to a plating solution reservoir. The semiconductor wafer is used as the cathode with an inert primary anode in the plating chamber and a remote consumable secondary anode in the plating solution reservoir for providing the metal ions for plating. The consumption of the consumable shielded secondary anode does not change the geometry or the electromotive force in the plating chamber and maintains a uniform thickness conductor core deposition which is easily planarized.
The present invention further provides a copper electroplating system for semiconductor wafers including a plating chamber having a consumable copper remote secondary anode connected by a recirculating system to a copper plating solution reservoir. The semiconductor wafer is used as the cathode with an inert platinum anode in the plating chamber and a remote consumable copper secondary anode in the plating solution reservoir for providing the metal ions for plating. The consumption of the consumable copper shielded secondary anode does not change the geometry or the electromotive force in the plating chamber and maintains a uniform thickness conductor core deposition which is easily planarized. The above and additional advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description when taken in conjunction with the accompanying drawings.